Better than all other things combined.

A common phrase is "Source \(x\) contributes more than all other sources combined." Which of the following is a necessary and sufficient condition for this to be true?

\(x\) contributes more than \(\frac{1}{n}\) of the total, where \(n\) is the number of sources\(x\) is responsible for more than 50% of the total\(x\) does not exist\(x\) contributes more than any other individual source